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                    函数
            
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                    泛型
            
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                    枚举
            
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                    类型推论
            
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                    类型兼容性
            
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                    高级类型
            
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                    实用工具类型
            
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                    Symbols
            
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                    Iterators 和 Generators
            
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                    模块
            
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                    命名空间和模块
            
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                    模块解析
            
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                    声明合并
            
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                    Decorators
            
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                    混入
            
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                    三斜线指令
            
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                    JavaScript文件里的类型检查
            
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                    如何书写声明文件
            
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                    结构
            
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                    规范
            
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                    举例
            
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                    深入
            
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                    发布
            
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                    使用
            
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                    工程配置
            
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                    tsconfig.json
            
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                    工程引用
            
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                    NPM包的类型
            
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                    编译选项
            
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                    配置 Watch
            
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                    在MSBuild里使用编译选项
            
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                    与其它构建工具整合
            
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                    使用TypeScript的每日构建版本
            
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                    Wiki
            
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                    TypeScript里的this
            
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                    编码规范
            
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                    常见编译错误
            
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        <li class="chapter " data-level="1.6.4" data-path="../wiki/TypeScript-Editor-Support.html">
            
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                    支持TypeScript的编辑器
            
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        <li class="chapter " data-level="1.6.5" data-path="../wiki/Using-TypeScript-With-ASP.NET-5.html">
            
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                    结合ASP.NET v5使用TypeScript
            
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        <li class="chapter " data-level="1.6.6" data-path="../wiki/Architectural-Overview.html">
            
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                    架构概述
            
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        <li class="chapter " data-level="1.6.7" data-path="../wiki/Roadmap.html">
            
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                    发展路线图
            
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        <li class="chapter " data-level="1.7" data-path="../release-notes/">
            
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                    新增功能
            
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        <li class="chapter " data-level="1.7.1" data-path="../release-notes/TypeScript 3.1.html">
            
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                    TypeScript 3.1
            
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        <li class="chapter " data-level="1.7.2" data-path="../release-notes/TypeScript 3.0.html">
            
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                    TypeScript 3.0
            
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        <li class="chapter " data-level="1.7.3" data-path="../release-notes/TypeScript 2.9.html">
            
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                    TypeScript 2.9
            
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        <li class="chapter " data-level="1.7.4" data-path="../release-notes/TypeScript 2.8.html">
            
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                    TypeScript 2.8
            
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        <li class="chapter " data-level="1.7.5" data-path="../release-notes/TypeScript 2.7.html">
            
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                    TypeScript 2.7
            
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        <li class="chapter " data-level="1.7.6" data-path="../release-notes/TypeScript 2.6.html">
            
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                    TypeScript 2.6
            
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        <li class="chapter " data-level="1.7.7" data-path="../release-notes/TypeScript 2.5.html">
            
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                    TypeScript 2.5
            
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        <li class="chapter " data-level="1.7.8" data-path="../release-notes/TypeScript 2.4.html">
            
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                    TypeScript 2.4
            
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        <li class="chapter " data-level="1.7.9" data-path="../release-notes/TypeScript 2.3.html">
            
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                    TypeScript 2.3
            
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        <li class="chapter " data-level="1.7.10" data-path="../release-notes/TypeScript 2.2.html">
            
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                    TypeScript 2.2
            
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        <li class="chapter " data-level="1.7.11" data-path="../release-notes/TypeScript 2.1.html">
            
                <a href="../release-notes/TypeScript 2.1.html">
            
                    
                    TypeScript 2.1
            
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        <li class="chapter " data-level="1.7.12" data-path="../release-notes/TypeScript 2.0.html">
            
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                    TypeScript 2.0
            
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        <li class="chapter " data-level="1.7.13" data-path="../release-notes/TypeScript 1.8.html">
            
                <a href="../release-notes/TypeScript 1.8.html">
            
                    
                    TypeScript 1.8
            
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        <li class="chapter " data-level="1.7.14" data-path="../release-notes/TypeScript 1.7.html">
            
                <a href="../release-notes/TypeScript 1.7.html">
            
                    
                    TypeScript 1.7
            
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        <li class="chapter " data-level="1.7.15" data-path="../release-notes/TypeScript 1.6.html">
            
                <a href="../release-notes/TypeScript 1.6.html">
            
                    
                    TypeScript 1.6
            
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        <li class="chapter " data-level="1.7.16" data-path="../release-notes/TypeScript 1.5.html">
            
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                    TypeScript 1.5
            
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        <li class="chapter " data-level="1.7.17" data-path="../release-notes/TypeScript 1.4.html">
            
                <a href="../release-notes/TypeScript 1.4.html">
            
                    
                    TypeScript 1.4
            
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        <li class="chapter " data-level="1.7.18" data-path="../release-notes/TypeScript 1.3.html">
            
                <a href="../release-notes/TypeScript 1.3.html">
            
                    
                    TypeScript 1.3
            
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        <li class="chapter " data-level="1.7.19" data-path="../release-notes/TypeScript 1.1.html">
            
                <a href="../release-notes/TypeScript 1.1.html">
            
                    
                    TypeScript 1.1
            
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                    Breaking Changes
            
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                    TypeScript 2.4
            
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        <li class="chapter " data-level="1.8.2" data-path="TypeScript 2.3.html">
            
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                    TypeScript 2.3
            
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                    TypeScript 2.2
            
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        <li class="chapter " data-level="1.8.4" data-path="TypeScript 2.1.html">
            
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                    TypeScript 2.1
            
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        <li class="chapter " data-level="1.8.5" data-path="TypeScript 2.0.html">
            
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                    TypeScript 2.0
            
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        <li class="chapter " data-level="1.8.6" data-path="TypeScript 1.8.html">
            
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                    TypeScript 1.8
            
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                    TypeScript 1.7
            
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                                <h1 id="typescript-24">TypeScript 2.4</h1>
<p>&#x5B8C;&#x6574;&#x7684;&#x7834;&#x574F;&#x6027;&#x6539;&#x52A8;&#x5217;&#x8868;&#x8BF7;&#x5230;&#x8FD9;&#x91CC;&#x67E5;&#x770B;:<a href="https://github.com/Microsoft/TypeScript/issues?q=is%3Aissue+milestone%3A%22TypeScript+2.4%22+label%3A%22Breaking+Change%22+is%3Aclosed" target="_blank">breaking change issues</a>&#x3002;</p>
<h2 id="&#x5F31;&#x7C7B;&#x578B;&#x68C0;&#x6D4B;">&#x5F31;&#x7C7B;&#x578B;&#x68C0;&#x6D4B;</h2>
<p>TypeScript 2.4&#x5F15;&#x5165;&#x4E86;&#x201C;&#x5F31;&#x7C7B;&#x578B;&#xFF08;weak type&#xFF09;&#x201D;&#x7684;&#x6982;&#x5FF5;&#x3002;
&#x82E5;&#x4E00;&#x4E2A;&#x7C7B;&#x578B;&#x53EA;&#x5305;&#x542B;&#x53EF;&#x9009;&#x7684;&#x5C5E;&#x6027;&#xFF0C;&#x90A3;&#x4E48;&#x5B83;&#x5C31;&#x88AB;&#x8BA4;&#x4E3A;&#x662F;<em>&#x5F31;&#xFF08;weak&#xFF09;</em>&#x7684;&#x3002;
&#x4F8B;&#x5982;&#xFF0C;&#x4E0B;&#x9762;&#x7684;<code>Options</code>&#x7C7B;&#x578B;&#x5C31;&#x662F;&#x4E00;&#x4E2A;&#x5F31;&#x7C7B;&#x578B;&#xFF1A;</p>
<pre><code class="lang-ts"><span class="hljs-keyword">interface</span> Options {
    data?: <span class="hljs-built_in">string</span>,
    timeout?: <span class="hljs-built_in">number</span>,
    maxRetries?: <span class="hljs-built_in">number</span>,
}
</code></pre>
<p>TypeScript 2.4&#xFF0C;&#x5F53;&#x7ED9;&#x4E00;&#x4E2A;&#x5F31;&#x7C7B;&#x578B;&#x8D4B;&#x503C;&#xFF0C;&#x4F46;&#x662F;&#x5B83;&#x4EEC;&#x4E4B;&#x524D;&#x6CA1;&#x6709;&#x5171;&#x540C;&#x7684;&#x5C5E;&#x6027;&#xFF0C;&#x90A3;&#x4E48;&#x5C31;&#x4F1A;&#x62A5;&#x9519;&#x3002;
&#x4F8B;&#x5982;&#xFF1A;</p>
<pre><code class="lang-ts"><span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-title">sendMessage</span>(<span class="hljs-params">options: Options</span>) </span>{
    <span class="hljs-comment">// ...</span>
}

<span class="hljs-keyword">const</span> opts = {
    payload: <span class="hljs-string">&quot;hello world!&quot;</span>,
    retryOnFail: <span class="hljs-literal">true</span>,
}

<span class="hljs-comment">// &#x9519;&#x8BEF;&#xFF01;</span>
sendMessage(opts);
<span class="hljs-comment">// &apos;opts&apos;&#x4E0E;&apos;Options&apos;&#x4E4B;&#x95F4;&#x6CA1;&#x6709;&#x5171;&#x540C;&#x7684;&#x5C5E;&#x6027;</span>
<span class="hljs-comment">// &#x4F60;&#x662F;&#x5426;&#x60F3;&#x7528;&apos;data&apos;/&apos;maxRetries&apos;&#x6765;&#x66FF;&#x6362;&apos;payload&apos;/&apos;retryOnFail&apos;</span>
</code></pre>
<p><strong>&#x63A8;&#x8350;&#x505A;&#x6CD5;</strong></p>
<ol>
<li>&#x4EC5;&#x58F0;&#x660E;&#x90A3;&#x4E9B;&#x786E;&#x5B9A;&#x5B58;&#x5728;&#x7684;&#x5C5E;&#x6027;&#x3002;</li>
<li>&#x7ED9;&#x5F31;&#x7C7B;&#x578B;&#x6DFB;&#x52A0;&#x7D22;&#x5F15;&#x7B7E;&#x540D;&#xFF08;&#x5982;&#xFF1A;<code>[propName: string]: {}</code>&#xFF09;</li>
<li>&#x4F7F;&#x7528;&#x7C7B;&#x578B;&#x65AD;&#x8A00;&#xFF08;&#x5982;&#xFF1A;<code>opts as Options</code>&#xFF09;</li>
</ol>
<h2 id="&#x63A8;&#x65AD;&#x8FD4;&#x56DE;&#x503C;&#x7684;&#x7C7B;&#x578B;">&#x63A8;&#x65AD;&#x8FD4;&#x56DE;&#x503C;&#x7684;&#x7C7B;&#x578B;</h2>
<p>TypeScript&#x73B0;&#x5728;&#x53EF;&#x4ECE;&#x4E0A;&#x4E0B;&#x6587;&#x7C7B;&#x578B;&#x4E2D;&#x63A8;&#x65AD;&#x51FA;&#x4E00;&#x4E2A;&#x8C03;&#x7528;&#x7684;&#x8FD4;&#x56DE;&#x503C;&#x7C7B;&#x578B;&#x3002;
&#x8FD9;&#x610F;&#x5473;&#x7740;&#x4E00;&#x4E9B;&#x4EE3;&#x7801;&#x73B0;&#x5728;&#x4F1A;&#x9002;&#x5F53;&#x5730;&#x62A5;&#x9519;&#x3002;
&#x4E0B;&#x9762;&#x662F;&#x4E00;&#x4E2A;&#x4F8B;&#x5B50;&#xFF1A;</p>
<pre><code class="lang-ts"><span class="hljs-keyword">let</span> x: Promise&lt;<span class="hljs-built_in">string</span>&gt; = <span class="hljs-keyword">new</span> Promise(resolve =&gt; {
    resolve(<span class="hljs-number">10</span>);
    <span class="hljs-comment">//      ~~ &#x9519;&#x8BEF;! &apos;number&apos;&#x7C7B;&#x578B;&#x4E0D;&#x80FD;&#x8D4B;&#x503C;&#x7ED9;&apos;string&apos;&#x7C7B;&#x578B;</span>
});
</code></pre>
<h2 id="&#x66F4;&#x4E25;&#x683C;&#x7684;&#x56DE;&#x8C03;&#x51FD;&#x6570;&#x53C2;&#x6570;&#x53D8;&#x5316;">&#x66F4;&#x4E25;&#x683C;&#x7684;&#x56DE;&#x8C03;&#x51FD;&#x6570;&#x53C2;&#x6570;&#x53D8;&#x5316;</h2>
<p>TypeScript&#x5BF9;&#x56DE;&#x8C03;&#x51FD;&#x6570;&#x53C2;&#x6570;&#x7684;&#x68C0;&#x6D4B;&#x5C06;&#x4E0E;&#x7ACB;&#x5373;&#x7B7E;&#x540D;&#x68C0;&#x6D4B;&#x534F;&#x53D8;&#x3002;
&#x4E4B;&#x524D;&#x662F;&#x53CC;&#x53D8;&#x7684;&#xFF0C;&#x8FD9;&#x4F1A;&#x5BFC;&#x81F4;&#x6709;&#x65F6;&#x5019;&#x9519;&#x8BEF;&#x7684;&#x7C7B;&#x578B;&#x4E5F;&#x80FD;&#x901A;&#x8FC7;&#x68C0;&#x6D4B;&#x3002;
&#x6839;&#x672C;&#x4E0A;&#x8BB2;&#xFF0C;&#x8FD9;&#x610F;&#x5473;&#x7740;&#x56DE;&#x8C03;&#x51FD;&#x6570;&#x53C2;&#x6570;&#x548C;&#x5305;&#x542B;&#x56DE;&#x8C03;&#x7684;&#x7C7B;&#x4F1A;&#x88AB;&#x66F4;&#x7EC6;&#x81F4;&#x5730;&#x68C0;&#x67E5;&#xFF0C;&#x56E0;&#x6B64;Typescript&#x4F1A;&#x8981;&#x6C42;&#x66F4;&#x4E25;&#x683C;&#x7684;&#x7C7B;&#x578B;&#x3002;
&#x8FD9;&#x5728;Promises&#x548C;Observables&#x4E0A;&#x662F;&#x5341;&#x5206;&#x660E;&#x663E;&#x7684;&#x3002;</p>
<h3 id="promises">Promises</h3>
<p>&#x4E0B;&#x9762;&#x662F;&#x6539;&#x8FDB;&#x540E;&#x7684;Promise&#x68C0;&#x67E5;&#x7684;&#x4F8B;&#x5B50;&#xFF1A;</p>
<pre><code class="lang-ts"><span class="hljs-keyword">let</span> p = <span class="hljs-keyword">new</span> Promise((c, e) =&gt; { c(<span class="hljs-number">12</span>) });
<span class="hljs-keyword">let</span> u: Promise&lt;<span class="hljs-built_in">number</span>&gt; = p;
    ~
    &#x7C7B;&#x578B; <span class="hljs-string">&apos;Promise&lt;{}&gt;&apos;</span> &#x4E0D;&#x80FD;&#x8D4B;&#x503C;&#x7ED9; <span class="hljs-string">&apos;Promise&lt;number&gt;&apos;</span>
</code></pre>
<p>TypeScript&#x65E0;&#x6CD5;&#x5728;&#x8C03;&#x7528;<code>new Promise</code>&#x65F6;&#x63A8;&#x65AD;&#x7C7B;&#x578B;&#x53C2;&#x6570;<code>T</code>&#x7684;&#x503C;&#x3002;
&#x56E0;&#x6B64;&#xFF0C;&#x5B83;&#x4EC5;&#x63A8;&#x65AD;&#x4E3A;<code>Promise&lt;{}&gt;</code>&#x3002;
&#x4E0D;&#x5E78;&#x7684;&#x662F;&#xFF0C;&#x5B83;&#x4F1A;&#x5141;&#x8BB8;&#x4F60;&#x8FD9;&#x6837;&#x5199;<code>c(12)</code>&#x548C;<code>c(&apos;foo&apos;)</code>&#xFF0C;&#x5C31;&#x7B97;<code>p</code>&#x7684;&#x58F0;&#x660E;&#x660E;&#x786E;&#x6307;&#x51FA;&#x5B83;&#x5E94;&#x8BE5;&#x662F;<code>Promise&lt;number&gt;</code>&#x3002;</p>
<p>&#x5728;&#x65B0;&#x7684;&#x89C4;&#x5219;&#x4E0B;&#xFF0C;<code>Promise&lt;{}&gt;</code>&#x4E0D;&#x80FD;&#x591F;&#x8D4B;&#x503C;&#x7ED9;<code>Promise&lt;number&gt;</code>&#xFF0C;&#x56E0;&#x4E3A;&#x5B83;&#x7834;&#x574F;&#x4E86;Promise&#x7684;&#x56DE;&#x8C03;&#x51FD;&#x6570;&#x3002;
TypeScript&#x4ECD;&#x65E0;&#x6CD5;&#x63A8;&#x65AD;&#x7C7B;&#x578B;&#x53C2;&#x6570;&#xFF0C;&#x6240;&#x4EE5;&#x4F60;&#x53EA;&#x80FD;&#x901A;&#x8FC7;&#x4F20;&#x9012;&#x7C7B;&#x578B;&#x53C2;&#x6570;&#x6765;&#x89E3;&#x51B3;&#x8FD9;&#x4E2A;&#x95EE;&#x9898;&#xFF1A;</p>
<pre><code class="lang-ts"><span class="hljs-keyword">let</span> p: Promise&lt;<span class="hljs-built_in">number</span>&gt; = <span class="hljs-keyword">new</span> Promise&lt;<span class="hljs-built_in">number</span>&gt;((c, e) =&gt; { c(<span class="hljs-number">12</span>) });
<span class="hljs-comment">//                                  ^^^^^^^^ &#x660E;&#x786E;&#x7684;&#x7C7B;&#x578B;&#x53C2;&#x6570;</span>
</code></pre>
<p>&#x5B83;&#x80FD;&#x591F;&#x5E2E;&#x52A9;&#x4ECE;promise&#x4EE3;&#x7801;&#x4F53;&#x91CC;&#x53D1;&#x73B0;&#x9519;&#x8BEF;&#x3002;
&#x73B0;&#x5728;&#xFF0C;&#x5982;&#x679C;&#x4F60;&#x9519;&#x8BEF;&#x5730;&#x8C03;&#x7528;<code>c(&apos;foo&apos;)</code>&#xFF0C;&#x4F60;&#x5C31;&#x4F1A;&#x5F97;&#x5230;&#x4E00;&#x4E2A;&#x9519;&#x8BEF;&#x63D0;&#x793A;:</p>
<pre><code class="lang-ts"><span class="hljs-keyword">let</span> p: Promise&lt;<span class="hljs-built_in">number</span>&gt; = <span class="hljs-keyword">new</span> Promise&lt;<span class="hljs-built_in">number</span>&gt;((c, e) =&gt; { c(<span class="hljs-string">&apos;foo&apos;</span>) });
<span class="hljs-comment">//                                                         ~~~~~</span>
<span class="hljs-comment">//  &#x53C2;&#x6570;&#x7C7B;&#x578B; &apos;&quot;foo&quot;&apos; &#x4E0D;&#x80FD;&#x8D4B;&#x503C;&#x7ED9; &apos;number&apos;</span>
</code></pre>
<h3 id="&#xFF08;&#x5D4C;&#x5957;&#xFF09;&#x56DE;&#x8C03;">&#xFF08;&#x5D4C;&#x5957;&#xFF09;&#x56DE;&#x8C03;</h3>
<p>&#x5176;&#x5B83;&#x7C7B;&#x578B;&#x7684;&#x56DE;&#x8C03;&#x4E5F;&#x4F1A;&#x88AB;&#x8FD9;&#x4E2A;&#x6539;&#x8FDB;&#x6240;&#x5F71;&#x54CD;&#xFF0C;&#x5176;&#x4E2D;&#x4E3B;&#x8981;&#x662F;&#x5D4C;&#x5957;&#x7684;&#x56DE;&#x8C03;&#x3002;
&#x4E0B;&#x9762;&#x662F;&#x4E00;&#x4E2A;&#x63A5;&#x6536;&#x56DE;&#x8C03;&#x51FD;&#x6570;&#x7684;&#x51FD;&#x6570;&#xFF0C;&#x56DE;&#x8C03;&#x51FD;&#x6570;&#x53C8;&#x63A5;&#x6536;&#x5D4C;&#x5957;&#x7684;&#x56DE;&#x8C03;&#x3002;
&#x5D4C;&#x5957;&#x7684;&#x56DE;&#x8C03;&#x73B0;&#x5728;&#x4F1A;&#x4EE5;&#x534F;&#x53D8;&#x7684;&#x65B9;&#x5F0F;&#x68C0;&#x67E5;&#x3002;</p>
<pre><code class="lang-ts">declare function f(
  callback: (nested: (error: number, result: any) =&gt; void, index: number) =&gt; void
): void;

f((nested: (error: number) =&gt; void) =&gt; { log(error) });
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
&apos;(error: number) =&gt; void&apos; &#x4E0D;&#x80FD;&#x8D4B;&#x503C;&#x7ED9; &apos;(error: number, result: any) =&gt; void&apos;
</code></pre>
<p>&#x4FEE;&#x590D;&#x8FD9;&#x4E2A;&#x95EE;&#x9898;&#x5F88;&#x5BB9;&#x6613;&#x3002;&#x7ED9;&#x5D4C;&#x5957;&#x7684;&#x56DE;&#x8C03;&#x4F20;&#x5165;&#x7F3A;&#x5931;&#x7684;&#x53C2;&#x6570;&#xFF1A;</p>
<pre><code class="lang-ts">f((nested: (error: <span class="hljs-built_in">number</span>, result: <span class="hljs-built_in">any</span>) =&gt; <span class="hljs-built_in">void</span>) =&gt; { });
</code></pre>
<h2 id="&#x66F4;&#x4E25;&#x683C;&#x7684;&#x6CDB;&#x578B;&#x51FD;&#x6570;&#x68C0;&#x67E5;">&#x66F4;&#x4E25;&#x683C;&#x7684;&#x6CDB;&#x578B;&#x51FD;&#x6570;&#x68C0;&#x67E5;</h2>
<p>TypeScript&#x5728;&#x6BD4;&#x8F83;&#x4E24;&#x4E2A;&#x5355;&#x4E00;&#x7B7E;&#x540D;&#x7684;&#x7C7B;&#x578B;&#x65F6;&#x4F1A;&#x5C1D;&#x8BD5;&#x7EDF;&#x4E00;&#x7C7B;&#x578B;&#x53C2;&#x6570;&#x3002;
&#x7ED3;&#x679C;&#x5C31;&#x662F;&#xFF0C;&#x5F53;&#x5173;&#x7CFB;&#x5230;&#x4E24;&#x4E2A;&#x6CDB;&#x578B;&#x7B7E;&#x540D;&#x65F6;&#x68C0;&#x67E5;&#x53D8;&#x5F97;&#x66F4;&#x4E25;&#x683C;&#x4E86;&#xFF0C;&#x4F46;&#x540C;&#x65F6;&#x4E5F;&#x4F1A;&#x6355;&#x83B7;&#x4E00;&#x4E9B;bug&#x3002;</p>
<pre><code class="lang-ts"><span class="hljs-keyword">type</span> A = &lt;T, U&gt;(x: T, y: U) =&gt; [T, U];
<span class="hljs-keyword">type</span> B = &lt;S&gt;(x: S, y: S) =&gt; [S, S];

<span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-title">f</span>(<span class="hljs-params">a: A, b: B</span>) </span>{
    a = b;  <span class="hljs-comment">// Error</span>
    b = a;  <span class="hljs-comment">// Ok</span>
}
</code></pre>
<p><strong>&#x63A8;&#x8350;&#x505A;&#x6CD5;</strong></p>
<p>&#x6216;&#x8005;&#x4FEE;&#x6539;&#x5B9A;&#x4E49;&#x6216;&#x8005;&#x4F7F;&#x7528;<code>--noStrictGenericChecks</code>&#x3002;</p>
<h2 id="&#x4ECE;&#x4E0A;&#x4E0B;&#x6587;&#x7C7B;&#x578B;&#x4E2D;&#x63A8;&#x8350;&#x7C7B;&#x578B;&#x53C2;&#x6570;">&#x4ECE;&#x4E0A;&#x4E0B;&#x6587;&#x7C7B;&#x578B;&#x4E2D;&#x63A8;&#x8350;&#x7C7B;&#x578B;&#x53C2;&#x6570;</h2>
<p>&#x5728;TypeScript&#x4E4B;&#x524D;&#xFF0C;&#x4E0B;&#x9762;&#x4F8B;&#x5B50;&#x4E2D;</p>
<pre><code class="lang-ts"><span class="hljs-keyword">let</span> f: &lt;T&gt;(x: T) =&gt; T = y =&gt; y;
</code></pre>
<p><code>y</code>&#x7684;&#x7C7B;&#x578B;&#x5C06;&#x662F;<code>any</code>&#x3002;
&#x8FD9;&#x610F;&#x5473;&#x7740;&#xFF0C;&#x7A0B;&#x5E8F;&#x867D;&#x4F1A;&#x8FDB;&#x884C;&#x7C7B;&#x578B;&#x68C0;&#x67E5;&#xFF0C;&#x4F46;&#x662F;&#x4F60;&#x53EF;&#x4EE5;&#x5728;<code>y</code>&#x4E0A;&#x505A;&#x4EFB;&#x4F55;&#x4E8B;&#xFF0C;&#x6BD4;&#x5982;&#xFF1A;</p>
<pre><code class="lang-ts"><span class="hljs-keyword">let</span> f: &lt;T&gt;(x: T) =&gt; T = y =&gt; y() + y.foo.bar;
</code></pre>
<p><strong>&#x63A8;&#x8350;&#x505A;&#x6CD5;:</strong></p>
<p>&#x9002;&#x5F53;&#x5730;&#x91CD;&#x65B0;&#x5BA1;&#x89C6;&#x4F60;&#x7684;&#x6CDB;&#x578B;&#x662F;&#x5426;&#x4E3A;&#x6B63;&#x786E;&#x7684;&#x7EA6;&#x675F;&#x3002;&#x5B9E;&#x5728;&#x4E0D;&#x884C;&#xFF0C;&#x5C31;&#x4E3A;&#x53C2;&#x6570;&#x52A0;&#x4E0A;<code>any</code>&#x6CE8;&#x89E3;&#x3002;</p>

                                
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